In a recent survey, 160 students had undergraduate degrees in arts, 63 had undergraduate degrees in science and 97 had graduate degrees. Art undergrads with graduate degree totaled 37 while 16 science undergrads also had graduate degrees. Some students had multiple degrees, 25 had both art and science undergraduate degrees while 16 had both art and science undergraduate degrees with a graduate degree. The number of students with only a science degree was?